Copper nitride (Cu3N) thin films were prepared on glass substrates by reactive rf magnetron sputtering. The film was decomposed into Cu film by healing 450 degreesC for 30 min. Nitrogen gas effused from the Cu3N film during the heating. The decomposition initiation temperature of the films was about 360 degreesC, and the thermal analysis involved thermogravimetry (TG) as well as a detection of N-2(+) ion that effused from the films during heating in a vacuum. Electron beam processing was used to decompose Cu3N into Cu. A dot array of 3 mum x 3 mum and 1 mum x 1 mum was obtained on the Cu3N film after electron beam irradiation. The Cu3N films easily dissolved in the dilute HCl solution. The etching rate of the Cu3N film in 100 g/l HCl aqueous solution was 3900 times that of the Cu film.